This application relates to a coated article including an anti-reflective layer(s) system. The anti-reflective layer(s) system may include one or more layers.
Coated articles are known in the art. For example, U.S. Pat. No. 5,800,933 discloses a coated article with a solar controlling layer system. The ""933 coated article includes: substrate/TiO2/Si3N4/NiCr/Ag/NiCr/Si3N4. In such coatings, the NiCr (nickel-chrome or nichrome) contact layers function to protect the Ag (silver) layer and also serve as adhesion and/or nucleation layers. The dielectric layers (i.e., TiO2, Si3N4) serve protective functions and also perform anti-reflection functions (i.e., they reduce visible reflectance), and as a result serve to increase transmission of the overall coated article.
Unfortunately, the coating of the ""933 Patent utilizes TiO2 as an underlayer. TiO2 often tends to be optically unstable with heat treatment (e.g., thermal tempering or heat bending of coated glass article). For example, TiO2 may change visibly upon heat treatment so that coated articles with the same coating thereon tend to look much different after heat treatment than their non-heat treated counterparts. This is not desirable when heat treated and non-heat treated coated articles have to be used side-by-side (e.g., in commercial buildings).
FIG. 1 is a cross sectional view of another prior art coated article. The FIG. 1 coated article includes: substrate/Si3N4/NiCr/Ag/NiCr/Si3N4. While coated articles such as that shown in FIG. 1 provide good ultraviolet (UV) and/or infrared (IR) reflection, they do face problems. Such problems often relate to meeting high visible transmission requirements imposed by industry standards and/or markets, while simultaneously satisfying UV and/or IR needs. The need for higher visible transmission often forces coating designers to minimize contact layer thicknesses and/or change contact layer materials to less absorbing and/or less durable options. The unfortunate consequence of this may be marginal durability of the coated article if high transmission requirements are to be met. In other words, it would be desirable if visible transmission of such articles could be increased and/or if visible reflection of such articles (glass side and/or film side) could be reduced while maintaining good durability.
Neutral color is also desirable for coated articles in many applications. Unfortunately, many conventional methods of making color of a coated article more neutral result in decreased visible transmission and/or increased visible reflection. Heretofore, it has been difficult to increase visible transmission and reduce visible reflection, while at the same time providing more neutral color and maintaining satisfactory solar control or thermal characteristics. Whether a color is xe2x80x9cneutralxe2x80x9d or not is subjective, and is a function of personal taste. However, generally speaking, color moving toward a neutral color target (e.g., a*=0, b*=0, or some other neutral color target such as transmissive a*=xe2x88x922 and transmissive b*=xe2x88x923.4) is desired.
In view of the above, it is an object of certain embodiments of this invention to provide a solar controlling coated article (i.e., an article including at least one layer for reflecting IR and/or UV) having increased visible transmission and/or reduced visible reflectance. In certain embodiments of this invention, it is an object to combine such high visible transmission and/or reduced visible reflectance with neutral color of the coated article. One or more of these objects is/are achieved by providing such coated articles with improved anti-reflection layer(s) system(s). Alternatively, the use of such improved anti-reflection layer(s) system(s) may enable coatings to have or utilize more robust contact layer(s) (e.g., thicker for better durability) and/or thicker silver (Ag) layer(s) (i.e., improved thermal performance) while maintaining similar transmission characteristics if increased transmission is not a most desired feature (e.g., if durability is a most desired feature).
Another object of this invention is to fulfill one or more of the above-listed objects and/or needs.
In certain example non-limiting embodiments of this invention, one or more of the above-listed objects and/or needs is/are satisfied by providing a coated article including a coating supported by a glass substrate, the coating comprising: a metallic infrared (IR) reflecting layer comprising silver sandwiched between first and second contact layers each of which contacts the IR reflecting layer; a first dielectric layer comprising silicon nitride provided between the IR reflecting layer and the glass substrate; a second dielectric layer comprising silicon oxynitride provided over the IR reflecting layer; a third dielectric layer comprising silicon oxide provided over the IR reflecting layer; and wherein the second dielectric layer comprising silicon oxynitride is provided between the IR reflecting layer and the third dielectric layer comprising silicon oxide.
In certain other example embodiments of this invention, one or more of the above-listed objects and/or needs is/are fulfilled by providing a coated article including a coating supported by a glass substrate, the coating comprising: a metallic infrared (IR) reflecting layer sandwiched between first and second contact layers; a first dielectric layer having an index of refraction n less than =3.0 provided between the IR reflecting layer and the glass substrate; a second dielectric layer comprising silicon nitride provided over the IR reflecting layer; a third dielectric layer comprising silicon oxynitride provided over the IR reflecting layer; and wherein the second dielectric layer comprising silicon nitride is provided between the IR reflecting layer and the third dielectric layer.
In certain other example embodiments of this invention, one or more of the above listed needs and/or objects is/are fulfilled by providing a coated article comprising a substrate, and a coating provided on the substrate, the coating comprising from the substrate outwardly: a dielectric layer; a layer comprising NiCr; a metallic IR reflecting layer comprising Ag; a layer comprising NiCr; and a layer comprising silicon oxynitride. The silicon oxynitride may or may not be oxidation/nitrogen graded in different embodiments of this invention.
Silicon oxynitride need not be provided in all embodiments herein, as exemplified by the embodiment where the overcoat portion of the AR system includes a silicon nitride layer and a silicon oxide layer.